Method of forming a component for an electric machine

ABSTRACT

A method of forming a winding for an electric machine includes forming a plurality of conductors having a substantially identical wire form with a plurality of end turns joining a plurality of slot segments, defining a first portion of the plurality of conductors as first conductors, rotating a second portion of the plurality of conductors about a central axis to mirror the first conductors, defining the second portion of the plurality of conductors as second conductors, combining select ones of the first conductors and select ones of the second conductors to form conductor pairs, and combining a plurality of conductor pairs to form a multi-conductor winding.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of an earlier filing date from U.S.Provisional Application No. 62/717,707 filed Aug. 10, 2018, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND

The stator of an electrical motor or generator includes two parts andinsulation material. The first part is the lamination. A lamination istypically formed of laminated sheets of electrical steel that is formed(stamped, rolled or bent) into an annulus shape having an ID, an OD anda stack height. The lamination further includes slots open to the ID orOD. The slots have a width and a depth. In between each slot is alamination tooth that extends from the ID or OD lamination back iron(yoke).

The second part is the winding. The winding is typically formed ofinsulated copper wire. It should be understood however, other conductivematerials, such as aluminum, might be used. The winding includes anumber of phases—typically 3, 5 or 6. The number of phases may vary. Foreach phase, the winding includes conductors having slot segments and endturns. The slot segments are housed in the lamination slots. The endturns span mostly circumferentially and connect two slot segmentstogether. The winding may be a delta winding or a wye winding.

A distributed winding is a winding that has poles of one phase thatinclude more than one slot, typically adjacent slots. Each phase mayalso occupy multiple winding layers. For example, in a 3 phase winding,there may be 24 poles, with two slots being occupied by each pole andthe winding may occupy 8 winding layers. Each pole may span three slots,but only occupy two slots at a time in any given winding layer. Thewinding should be electrically balanced in order to minimize losses andincrease efficiency. Creating an electrically balanced winding that maybe introduced into more compact stators is a challenge. Further, formingconductors into winding shapes that may be inserted into the laminationto form a balanced winding is a time consuming and challenging endeavor.Accordingly, the industry would be receptive of a system that forms abalanced stator winding that has a reduced thickness and which mayinclude windings that are easily formed, combined, and introduced into alamination.

SUMMARY

Disclosed is a method of forming a winding for an electric machineincluding forming a plurality of conductors having a substantiallyidentical wire form with a plurality of end turns joining a plurality ofslot segments, defining a first portion of the plurality of conductorsas first conductors, rotating a second portion of the plurality ofconductors about a central axis to mirror the first conductors, definingthe second portion of the plurality of conductors as second conductors,combining select ones of the first conductors and select ones of thesecond conductors to form conductor pairs, and combining a plurality ofconductor pairs to form a multi-conductor winding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a stator for an electric motor including a winding,formed in accordance with an aspect of an exemplary embodiment;

FIG. 2 depicts a first conductor of the winding of the stator of FIG. 1,in accordance with an aspect of an exemplary embodiment;

FIG. 3 depicts a second conductor of the winding of the stator of FIG.1, in accordance with an aspect of an exemplary embodiment;

FIG. 4 depicts a conductor pair including a first conductor and a secondconductor, in accordance with an aspect of an exemplary embodiment;

FIG. 5 depicts a portion of the conductor pair of FIG. 4, in accordancewith an exemplary aspect;

FIG. 6 depicts a first multi-conductor winding of the stator of FIG. 1,in accordance with an aspect of an exemplary embodiment;

FIG. 7 depicts a second multi-conductor winding of the stator of FIG. 1,in accordance with an aspect of an exemplary embodiment; and

FIG. 8 depicts a second multi-conductor winding overlaid onto the firstmulti-conductor winding to form the winding of the stator of FIG. 1, inaccordance with an aspect of an exemplary embodiment.

DETAILED DESCRIPTION

A stator for an electric machine is indicated generally at 10 in FIG. 1.Stator 10 includes a stator body 12 that supports a windings 14 formedfrom a plurality of conductors 16. Stator body 12 may be formed from anelectrically conductive material and includes a plurality of slots (notshown) which, in the embodiment shown, are formed in an inner annularsurface (also not shown). Windings 14 include a woven section 18 and aconnector lead section 20. Woven section 18 defines a portion of winding14 at which point conductors may be interlaced to establish a desiredform factor and electrical balance. Connector lead section 20 defines aportion at terminal ends of the conductors forming winding 14 may beinterconnected and coupled to, for example, a power source.

Winding 14 is formed by creating woven conductor pairs of AB conductorsand C/D conductors. As will become apparent herein, a B conductor mayrepresent a mirror image of an A conductor and a D conductor mayrepresent a mirror image of a C conductor, with the A and C conductorsbeing substantially identical and the B and D conductors beingsubstantially identical. Further, as will become readily apparentherein, each of the conductors A, B, C, and D includes an identical formand may only differ by an orientation relative to, for example, aselected axis.

In an exemplary embodiment, plurality of conductors 16 each have asubstantially identical wire form or geometry. A portion of plurality ofconductors 16 is selected as first conductors, one of which is shown at34 in FIG. 2. First conductor 34 includes a first end 36, a second end37, a plurality of end turns 39 joining a plurality of slot segments,one of which is shown at 40, extending therebetween. The plurality ofend turns 39 may have a triangular or gabled shape, such as shown inFIG. 2. First conductor 34 may represent either an A conductor or a Cconductor depending upon position as will be detailed herein. Firstconductor 34 may include a central axis 42. The central axis 42 issubstantially parallel to the plurality of slot segments. As can be seenin FIG. 2 or FIG. 3, there plurality of conductors 16 are formed with atleast 12 end turns 39 disposed on the right of the central axis and atleast 12 end turns 39 disposed on the left of the central axis. Firstend 36 of first conductor 34 defines a first connector lead 41 andsecond end 37 defines a second connector lead 43. The central axis 42 islocated equal distance from first connector lead 41 and second connectorlead 43. Plurality of end turns 39 include a first plurality of bends44A having a first winding pitch X1, a second plurality of bends 44Bhaving the first winding pitchy X1, and a third plurality of bends 44Chaving the first winding pitch X1. Plurality of end turns 39 alsoinclude a bend 46 having a second winding pitch X2 and a bend 48 havinga third winding pitch X3. The bend 46 is located on one side of thecentral axis 42 and the bend 48 is located on the opposite side ofcentral axis 42. The central axis 42 is located equal distance from thebend 46 and the bend 48.

In accordance with an exemplary aspect, second winding pitch X2 may beone greater than first winding pitch X1 and third winding pitch X3 maybe one less than first winding pitch X1. In an embodiment, first windingpitch X1 may represent a 6 pitch, second winding pitch X2 may representa 7 pitch, and third winding pitch X3 may represent a 5 pitch. Theparticular pitch value may vary. The phrase 6 pitch describes that aparticular end turn connects two slot segments that span over 5 slots.

In further accordance with an exemplary embodiment, another portion ofplurality of conductors 16 are selected as second conductors 52 as shownin FIG. 3. Second conductor 52 is a mirror image of first conductor 34.That is, first conductor 34 may be rotated 180° about central axis 42 toform second conductor 52. After the first conductor 34 is rotated 180degrees, the first connector lead 41 swaps positions with the secondconnector lead 43 and the bend 46 swaps position with bend 48. Secondconductor 52 may define wither a B conductor or a D conductor as will bediscussed herein. As will be detailed herein, a first conductor 34 iscombined with a second conductor 52 to form a conductor pair 54 as shownin FIG. 4. When introduced into stator body 12, first conductor 34 andsecond conductor 52 will reside in adjacent slots. First conductor 34and second conductor 52 may be combined such that bend 48 having thethird winding pitch X3 of second conductor 52 nests within bend 46having the second pitch of first conductor 34 as shown in FIG. 5. Thenesting allows for conductor pair 54 to possess a reduce thickness aswill be detailed herein.

In an embodiment, multiple conductor pairs 54 are combined to form afirst multi-conductor winding 90 as shown in FIG. 6. At this point, itshould be understood that first multi-conductor winding 90 is formed byoverlaying three conductor pairs 54 of AB conductors. Thus, firstmulti-conductor winding 90 may take the form of a six conductor windingin an exemplary embodiment. At this point, a second multi-conductorwinding 94 is formed in a manner similar to that of firstmulti-conductor winding 90. Second multi-conductor winding 94 is formedby overlaying three conductor pairs (not separately labeled) of C/Dconductors as shown in FIG. 7.

Second multi-conductor winding 94 may be overlaid onto firstmulti-conductor winding 90 to form a Phase winding 100 of stator 10 asshown in FIG. 8. Phase winding 100 includes twelve conductors, inaccordance with an exemplary embodiment. When introduced into statorbody 12, second multi-conductor winding 94 may be located one (1) polefrom first multi-conductor winding 90. In an embodiment, secondmulti-conductor winding 94 may be interleaved with first multi-conductorwinding 90 in order to improve the electrical balancing of phase winding100. Additional phase windings (not shown) may be formed in a similarmanner and introduced into stator body 12 to form plurality of windings14.

In an exemplary embodiment, plurality of windings 14 has only one shapeand two orientations of wires A, C and B, D. It is understood that othercombinations of wires exist. For a stator having 3 slots per pole perphase and 3 phases, the common pitch is 9 and the special pitch areasare 11 pitch over two eight pitches. In such a design, there may bethree distinct wire shapes and the one is the mirror image of one of theother shapes. The process of forming a stator having 3 slots per poleper phase and 3 phases is similar to the process described above but twowire formers are required and only every third wire is rotated 180degrees left to right.

At this point, it should be understood that the exemplary embodimentsdescribe a system for forming a stator having a winding formed frommultiple conductors each having an identical geometry. That is, eachwinding conductor is formed, manipulated, and combined with otherwinding conductors to form a plurality of windings for an electricmachine. While described as being formed from first and second windings,it should be understood that the phase winding could include three ormore windings. After insertion the windings could be connected in aDelta configuration or a wye configuration.

The terms “about” and “substantially” are intended to include the degreeof error associated with measurement of the particular quantity basedupon the equipment available at the time of filing the application. Forexample, “about” and/or “substantially” can include a range of ±8% or5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, element components,and/or groups thereof.

While the invention has been described with reference to an exemplaryembodiment or embodiments, it will be understood by those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe claims.

What is claimed is:
 1. A method of forming a winding for an electricmachine comprising: forming a plurality of conductors having asubstantially identical wire form with a plurality of end turns joininga plurality of slot segments; defining a first portion of the pluralityof conductors as first conductors; rotating a second portion of theplurality of conductors about a central axis to mirror the firstconductors; defining the second portion of the plurality of conductorsas second conductors; combining select ones of the first conductors andselect ones of the second conductors to form conductor pairs; andcombining a plurality of conductor pairs to form a multi-conductorwinding.
 2. The method of claim 1, wherein combining select ones of thefirst conductors and select ones of the second conductors includesnesting one of the end turns of one of the second conductors within oneof the end turns of one of the first conductors.
 3. The method of claim2, wherein combining select ones of the first conductors and select onesof the second conductors includes nesting an end turn of one of thefirst conductors between slot segments of one of the second conductors.4. The method of claim 1, wherein combining the plurality of conductorpairs includes combining a first conductor pair, a second conductorpair, and a third conductor pair to form a six-conductor winding.
 5. Themethod of claim 1, further comprising: combining a first multi-conductorwinding and a second multi-conductor winding to form at least a portionof a stator winding for the electric machine.
 6. The method of claim 1,wherein forming the plurality of conductors includes forming a pluralityof conductors having a plurality of end turns having at least threedistinct winding pitches.
 7. The method of claim 6, wherein forming thea plurality of conductors having the plurality of end turns having atleast three distinct winding pitches includes forming a first portion ofthe plurality of end turns to include a first winding pitch, at leastone of the plurality of end turns to include a second winding pitch thatis distinct from the first winding pitch, and at least one other of theplurality of end turns to include a third winding pitch that is distinctfrom the first and second winding pitches.
 8. The method of claim 7,wherein forming the at least one of the plurality of end turns toinclude the second winding pitch includes forming the at least one ofthe plurality of end turns to include a winding pitch that is onegreater than the first winding pitch.
 9. The method of claim 8, whereinforming the at least one other of the plurality of end turns to includethe third winding pitch includes forming the at least one other of theplurality of end turns to include a winding pitch that is one less thanthe first winding pitch.
 10. The method of claim 8, wherein forming theplurality of conductors includes forming the end turns having atriangular shape.
 11. The method of claim 10, wherein forming one of thesecond conductors further includes forming a second conductor having atleast 12 end turns disposed on one side of the central axis and at least12 end turns disposed on an opposite side of the central axis.
 12. Themethod of claim 7, wherein forming one of the second conductors furtherincludes locating the central axis of the one of the second conductorsan equal distance from the end turn having the second winding pitch andthe end turn having the third winding pitch.
 13. The method of claim 12,wherein forming one of the second conductors with a first connector leadand a second connector lead and locating the central axis of the one ofthe second conductors an equal distance from the first connector leadand the second connector lead.
 14. The method of claim 1, wherein thecentral axis of the second conductors are located substantially parallelto slot segments of the second conductors.
 15. The method of claim 1,further comprising: positioning the multi-conductor winding in a statorbody of an electric machine.
 16. An electric machine comprising: astator including a stator body and a plurality of windings formed fromthe method of claim 1.